Si, Qimiao2009-06-042009-06-042004Sun, Jun. "Impurity effects in interacting quantum many-body systems." (2004) Diss., Rice University. <a href="https://hdl.handle.net/1911/18819">https://hdl.handle.net/1911/18819</a>.https://hdl.handle.net/1911/18819Impurities have a wide range of effects in interacting quantum many-body systems. They can interplay with interactions and lead to new electronic states of matter. They can also serve as a probe of an "intrinsic" many-body system. In this thesis, we consider the effects of impurities in three quantum many-body systems. First, we study the transport properties of a two-dimensional interacting electronic system with dilute quenched disorder. We find that the ground state is in fact a metallic state and in-plane magnetic-field can drive it to an insulating one. Second, we address the orthogonality catastrophe in Bose-Einstein condensate with a local impurity at its center. It is shown that the orthogonality effect in a Bose system has a stretched-exponential form, stronger than the algebraic orthogonality of a Fermi counterpart. The corresponding absorption spectrum is also determined. Finally, we analyze the effects of a spin resonance mode on the scattering tunneling microscopy(STM) spectra of a d-wave superconductor near a potential scattering center. We identify a counterintuitive two-unit-cell spatial modulation, at o &sime; +/-(Delta0 + O0)/h, where Delta 0 is the energy gap and O0 is the resonance mode energy. This effect can be tested by the Fourier-transformed STM technique.95 p.application/pdfengCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.PhysicsElectromagneticsCondensed matter physicsAtomic physicsThesisTHESIS PHYS. 2005 SUN